A. Field of the Invention
This invention is related to short chain diesters, and more particularly to a process for the obtention of a product with a high content of zeaxanthin, lutein or mixtures thereof, as short chain organic acid diesters of zeaxantine, lutein or mixtures thereof.
B. Description of the Related Art
The yellow carotenoids such as the lutein and the zeaxanthin, occur in marigold flowers as mono- or diesters, linked to long chain fatty acids such as palmitic, stearic or myristic acids, among others (Alam, A. U. (1968) Lipids, 3(2), 183; Gayle G. (1986) J. Food Sci., 51(4), 1093).
It is assumed that in such chemical structure, the carotenoids are better protected against oxydative processes, so that the flower color is better preserved in nature.
However, in the pigmentation of broilers, it has been shown that the bioavailability of such carotenoid fatty esters is lower than when they are hydrolized, i.e. when they are fed as free carotenoids (Coon, C. N. (1976) Poult. Sci., 551 841-847).
Applicant's have found that by saponification of the marigold carotenoids and their subsquent linking to short chain acids, such as formic, acetic or propionic, etc., an improvement in their bioavailability, and that a more stable form of the carotenoids is achieved.
The acetylation of carotenoids, zeaxanthin among others, has been carried out in laboratory scale since decades ago. The reported methodology specifically refers to a research, for elucidation purposes about the chemical structures of the carotenoids.
The carotenoid in pure form, zeaxanthin in this case, is dissolved in pyridine treating it with acetic anhydride and agitation at room temperature to obtain the acetylated derivative after several hours (Liaaen-Jensen, S. and Jensen, A. (1971) Methods Enzymol. 23, 586), or in a few minutes if the reactants mixture is maintained under reflux (Alam, 1968).
Another preferred chemical path to obtain the acetylated compound is to dissolve the zeaxanthin in pyridine and benzene to carry on the reaction at 20.degree. C. with acetyl chloride, a few minutes later (Bartlett, L. (1969) J. Chem. Soc. C, 2538).
In the process acording with the present invention, marigold extracts containing saponified and isomerized carotenoids (Torres, et al. 5,523,494 6/1996, 568/834), are treated directly with acetic anhydride, or propionic anhydride in such a way as to obtain the short chain organic acid diester derivatives of the zeaxanthin, lutein or mixtures thereof, present in such extracts.